Preheat your air fryer to 375°F (190°C) for about 5 minutes while you prepare the Brussels sprouts.
Rinse the Brussels sprouts under cold water. Trim the stem ends and remove any yellow or damaged leaves.
Cut the Brussels sprouts in half lengthwise for better cooking and flavor absorption.
In a mixing bowl, combine the halved Brussels sprouts, olive oil, garlic powder, salt, and black pepper. Toss them until evenly coated.
Place the Brussels sprouts in the air fryer basket in a single layer, ensuring they are not overcrowded.
Cook in the air fryer for 12 to 15 minutes, shaking the basket halfway through to ensure even cooking. The sprouts should be golden brown and crispy.
If desired, toss the cooked Brussels sprouts with balsamic vinegar and grated Parmesan cheese before serving for added flavor.
Transfer the Brussels sprouts to a serving dish and enjoy!